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From: Jens Axboe <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>, Alex Xu <[email protected]>
Subject: [PATCH 32/33] io_uring: ensure that threads freeze on suspend
Date: Wed,  3 Mar 2021 17:26:59 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

Alex reports that his system fails to suspend using 5.12-rc1, with the
following dump:

[  240.650300] PM: suspend entry (deep)
[  240.650748] Filesystems sync: 0.000 seconds
[  240.725605] Freezing user space processes ...
[  260.739483] Freezing of tasks failed after 20.013 seconds (3 tasks refusing to freeze, wq_busy=0):
[  260.739497] task:iou-mgr-446     state:S stack:    0 pid:  516 ppid:   439 flags:0x00004224
[  260.739504] Call Trace:
[  260.739507]  ? sysvec_apic_timer_interrupt+0xb/0x81
[  260.739515]  ? pick_next_task_fair+0x197/0x1cde
[  260.739519]  ? sysvec_reschedule_ipi+0x2f/0x6a
[  260.739522]  ? asm_sysvec_reschedule_ipi+0x12/0x20
[  260.739525]  ? __schedule+0x57/0x6d6
[  260.739529]  ? del_timer_sync+0xb9/0x115
[  260.739533]  ? schedule+0x63/0xd5
[  260.739536]  ? schedule_timeout+0x219/0x356
[  260.739540]  ? __next_timer_interrupt+0xf1/0xf1
[  260.739544]  ? io_wq_manager+0x73/0xb1
[  260.739549]  ? io_wq_create+0x262/0x262
[  260.739553]  ? ret_from_fork+0x22/0x30
[  260.739557] task:iou-mgr-517     state:S stack:    0 pid:  522 ppid:   439 flags:0x00004224
[  260.739561] Call Trace:
[  260.739563]  ? sysvec_apic_timer_interrupt+0xb/0x81
[  260.739566]  ? pick_next_task_fair+0x16f/0x1cde
[  260.739569]  ? sysvec_apic_timer_interrupt+0xb/0x81
[  260.739571]  ? asm_sysvec_apic_timer_interrupt+0x12/0x20
[  260.739574]  ? __schedule+0x5b7/0x6d6
[  260.739578]  ? del_timer_sync+0x70/0x115
[  260.739581]  ? schedule_timeout+0x211/0x356
[  260.739585]  ? __next_timer_interrupt+0xf1/0xf1
[  260.739588]  ? io_wq_check_workers+0x15/0x11f
[  260.739592]  ? io_wq_manager+0x69/0xb1
[  260.739596]  ? io_wq_create+0x262/0x262
[  260.739600]  ? ret_from_fork+0x22/0x30
[  260.739603] task:iou-wrk-517     state:S stack:    0 pid:  523 ppid:   439 flags:0x00004224
[  260.739607] Call Trace:
[  260.739609]  ? __schedule+0x5b7/0x6d6
[  260.739614]  ? schedule+0x63/0xd5
[  260.739617]  ? schedule_timeout+0x219/0x356
[  260.739621]  ? __next_timer_interrupt+0xf1/0xf1
[  260.739624]  ? task_thread.isra.0+0x148/0x3af
[  260.739628]  ? task_thread_unbound+0xa/0xa
[  260.739632]  ? task_thread_bound+0x7/0x7
[  260.739636]  ? ret_from_fork+0x22/0x30
[  260.739647] OOM killer enabled.
[  260.739648] Restarting tasks ... done.
[  260.740077] PM: suspend exit

Play nice and ensure that any thread we create will call try_to_freeze()
at an opportune time so that memory suspend can proceed. For the io-wq
worker threads, mark them as PF_NOFREEZE. They could potentially be
blocked for a long time.

Reported-by: Alex Xu (Hello71) <[email protected]>
Tested-by: Alex Xu (Hello71) <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
---
 fs/io-wq.c    | 3 +++
 fs/io_uring.c | 5 ++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 1fdb2b621b51..a44bd22c045e 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -16,6 +16,7 @@
 #include <linux/rculist_nulls.h>
 #include <linux/cpu.h>
 #include <linux/tracehook.h>
+#include <linux/freezer.h>
 
 #include "../kernel/sched/sched.h"
 #include "io-wq.h"
@@ -263,6 +264,7 @@ static void io_wqe_dec_running(struct io_worker *worker)
 
 static void io_worker_start(struct io_worker *worker)
 {
+	current->flags |= PF_NOFREEZE;
 	worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
 	io_wqe_inc_running(worker);
 	complete(&worker->started);
@@ -731,6 +733,7 @@ static int io_wq_manager(void *data)
 		set_current_state(TASK_INTERRUPTIBLE);
 		io_wq_check_workers(wq);
 		schedule_timeout(HZ);
+		try_to_freeze();
 		if (fatal_signal_pending(current))
 			set_bit(IO_WQ_BIT_EXIT, &wq->state);
 	} while (!test_bit(IO_WQ_BIT_EXIT, &wq->state));
diff --git a/fs/io_uring.c b/fs/io_uring.c
index d9161b181a21..7cf8d4a99d91 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -74,13 +74,11 @@
 #include <linux/fsnotify.h>
 #include <linux/fadvise.h>
 #include <linux/eventpoll.h>
-#include <linux/fs_struct.h>
 #include <linux/splice.h>
 #include <linux/task_work.h>
 #include <linux/pagemap.h>
 #include <linux/io_uring.h>
-#include <linux/blk-cgroup.h>
-#include <linux/audit.h>
+#include <linux/freezer.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/io_uring.h>
@@ -6736,6 +6734,7 @@ static int io_sq_thread(void *data)
 				io_ring_set_wakeup_flag(ctx);
 
 			schedule();
+			try_to_freeze();
 			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
 				io_ring_clear_wakeup_flag(ctx);
 		}
-- 
2.30.1


  parent reply	other threads:[~2021-03-04  1:10 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-04  0:26 [PATCHSET 0/33] Fixes queued up for 5.12 Jens Axboe
2021-03-04  0:26 ` [PATCH 01/33] io-wq: wait for worker startup when forking a new one Jens Axboe
2021-03-04  0:26 ` [PATCH 02/33] io-wq: have manager wait for all workers to exit Jens Axboe
2021-03-04  0:26 ` [PATCH 03/33] io-wq: don't ask for a new worker if we're exiting Jens Axboe
2021-03-04  0:26 ` [PATCH 04/33] io-wq: rename wq->done completion to wq->started Jens Axboe
2021-03-04  0:26 ` [PATCH 05/33] io-wq: wait for manager exit on wq destroy Jens Axboe
2021-03-04  0:26 ` [PATCH 06/33] io-wq: fix double put of 'wq' in error path Jens Axboe
2021-03-04  0:26 ` [PATCH 07/33] io_uring: SQPOLL stop error handling fixes Jens Axboe
2021-03-04  0:26 ` [PATCH 08/33] io_uring: run fallback on cancellation Jens Axboe
2021-03-04  0:26 ` [PATCH 09/33] io_uring: don't use complete_all() on SQPOLL thread exit Jens Axboe
2021-03-04  0:26 ` [PATCH 10/33] io-wq: provide an io_wq_put_and_exit() helper Jens Axboe
2021-03-04  0:26 ` [PATCH 11/33] io_uring: fix race condition in task_work add and clear Jens Axboe
2021-03-04  0:26 ` [PATCH 12/33] io_uring: signal worker thread unshare Jens Axboe
2021-03-04 12:15   ` Stefan Metzmacher
2021-03-04 14:05     ` Jens Axboe
2021-03-04  0:26 ` [PATCH 13/33] io_uring: warn on not destroyed io-wq Jens Axboe
2021-03-04  0:26 ` [PATCH 14/33] io_uring: destroy io-wq on exec Jens Axboe
2021-03-04  0:26 ` [PATCH 15/33] io_uring: remove unused argument 'tsk' from io_req_caches_free() Jens Axboe
2021-03-04  0:26 ` [PATCH 16/33] io_uring: kill unnecessary REQ_F_WORK_INITIALIZED checks Jens Axboe
2021-03-04  0:26 ` [PATCH 17/33] io_uring: move cred assignment into io_issue_sqe() Jens Axboe
2021-03-04  0:26 ` [PATCH 18/33] io_uring: kill unnecessary io_run_ctx_fallback() in io_ring_exit_work() Jens Axboe
2021-03-04  0:26 ` [PATCH 19/33] io_uring: kill io_uring_flush() Jens Axboe
2021-03-04  0:26 ` [PATCH 20/33] io_uring: fix __tctx_task_work() ctx race Jens Axboe
2021-03-04  0:26 ` [PATCH 21/33] io_uring: replace cmpxchg in fallback with xchg Jens Axboe
2021-03-04  0:26 ` [PATCH 22/33] io_uring: ensure that SQPOLL thread is started for exit Jens Axboe
2021-03-04  0:26 ` [PATCH 23/33] io_uring: ignore double poll add on the same waitqueue head Jens Axboe
2021-03-04  0:26 ` [PATCH 24/33] io_uring: kill sqo_dead and sqo submission halting Jens Axboe
2021-03-04  0:26 ` [PATCH 25/33] io_uring: remove sqo_task Jens Axboe
2021-03-04  0:26 ` [PATCH 26/33] io-wq: fix error path leak of buffered write hash map Jens Axboe
2021-03-04  0:26 ` [PATCH 27/33] io_uring: fix -EAGAIN retry with IOPOLL Jens Axboe
2021-03-04  0:26 ` [PATCH 28/33] io_uring: choose right tctx->io_wq for try cancel Jens Axboe
2021-03-04  0:26 ` [PATCH 29/33] io_uring: inline io_req_clean_work() Jens Axboe
2021-03-04  0:26 ` [PATCH 30/33] io_uring: inline __io_queue_async_work() Jens Axboe
2021-03-04  0:26 ` [PATCH 31/33] io_uring: remove extra in_idle wake up Jens Axboe
2021-03-04  0:26 ` Jens Axboe [this message]
2021-03-04  0:27 ` [PATCH 33/33] io-wq: ensure all pending work is canceled on exit Jens Axboe

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